The girls were found Aug. 25 in San Antonio, after frantic worry by their families and a prayer vigil the night before at the church both girls attend.

Early in their disappearance, authorities believed that a man they met on Facebook lured them to San Antonio, where the car was found abandoned Aug. 20, said Deputy Thomas Gilliland, spokesman for the Harris County Sheriff's Office.

When investigators analyzed the girls' computers, they found that the man they supposedly went to meet didn't exist, Gilliland said.

"It was a fictitious Facebook page that was created by one of the girls," he said.

The teen had used her father's work computer at home to make up a profile for the man she called Shawn Hernandez, he said.

"The ruse they created was quite elaborate for two juveniles," Gilliland said. "These are the type of children who have grown up to be social-media savvy."

The girls also revealed their intentions by keeping detailed, handwritten journals, which they left at home.

"They were pinpointing the times it took to go between Houston and San Antonio, Houston to Dallas, Houston to Denver," he said. "They had everything pretty meticulously planned out. 'Four minutes for a restroom break and then back on the road.' "

Also, from the computer, they had printed maps and road directions to other cities, which they copied by hand into their journals, he said.

Their plans unraveled in San Antonio, where police impounded the car because the Harris County Sheriff's Office had reported it stolen, standard procedure in a runaway case, Gilliland said.

The girls' backpacks, with most of their money and supplies, were in the car when police had it towed, so they ended up panhandling Aug. 24 in front of a San Antonio store.

Store employees called police, who contacted the girls' parents.

The teens will not be charged, Gilliland said.

"We weren't very happy when we found out it was a ruse, but this is our job," he said. "This is what we do. I hope it's a good life lesson for them. This could have ended a whole different way."

It can also be a lesson for parents, Gilliland said, to be aware of what their children are doing online.

"It's good to have your kids computer savvy, but you need to be a responsible parent and know the sites they visit," he said. "Either they show you or you find out what they're looking at."